Nuclear and electron spin resonance have proven invaluable in elucidating the structure and dynamics of biomembranes. Current work includes: - Parallelization of the major simulation codes using the Message Passing Interface; - Implementation of direct numerical evaluation of analytic derivatives needed for automated non-linear least squares fitting of experimental spectra; - Development of new theoretical and computational techniques for investigating the response of complicated coupled spin systems to arbitrary resonance irradiation fields - Exploitation of new iterative techniques for the iterative solution of complex non-Hermitian linear systems and associated eigenvalue problems. The software for simulating slow motional magnetic resonance spectra developed in Freed's group is widely distributed and has become the de facto standard for analyzing experimental data for this class of biomembrane problems. The same theory and computational techniques are also useful for the analysis of spin-labeled biopolymers such as DNA and proteins.